Morphometric and Molecular Muscle Remodeling after Passive Stretching in Elderly Female Rats

Abstract

To determine the effects of three sessions of a passive stretching exercise protocol on the muscles of elderly female rats. METHODS: The effects of the stretching exercises on the soleus muscle were analyzed using immunohistochemistry [tissue inhibitors of matrix metalloproteinases (TIMP), the tumor necrosis factor-alpha (TNF-a), and the gene expression levels using real-time PCR of the transforming growth factor-beta 1 (TGF-b1), collagen type 1 (COL1), and collagen type 3 (COL3)]. Fifteen 26-month-old female Wistar rats were randomly divided into two groups, namely, Stretching (SG, n=8) and Control (CG, n=7). The passive mechanical stretching protocol consisted of a set of 4 1-minute repetitions, with 30 seconds between each repetition (total treatment of 4 minutes), three times a week for 1 week. RESULTS: Immunohistochemical analysis revealed an increase of 71.4% in the TNF-a (p=0.04) gene expression levels for the SG and a 58% decrease in the TGF-b1 gene expression levels (p=0.005) in the SG compared to that in the CG. No significant differences were observed between the groups for the immunostaining of TIMP-1 or the gene expression levels of COL1 and COL3. CONCLUSION: Three sessions of static stretching reduced the gene expression level of TGF-b1, which, owing to its anti-fibrotic role, might contribute to the remodeling of the intramuscular connective tissue of the aging muscle. In addition, immunostaining revealed that TNF-a levels increased in the aging muscle tissue in response to stretching, indicating its effect on stimulating extracellular matrix degradation. These outcomes have important clinical implications in reinforcing the use of stretching exercises in the elderly, considering that the aging muscle presents an infiltration of connective tissue.

Peripubertal Exposure to Glyphosate-Based Herbicides Promotes Histopathological Impairment in the Structure of the Diaphragm Muscle of C57BL/6 Mice

“…Finally, the connective envelopes are responsible for the structural maintenance of muscle fibers and for allowing the individually generated force of contraction to act on the entire muscle. It is important to note that several pathological alterations in the muscle are also associated with some degree of thickening of the extracellular matrix, or the collagen composition of this matrix (45). Therefore, due to muscle damage caused by exposure to GBH, there may be an imbalance in the proliferation of growth factors involved in muscle regeneration and mesenchymal growth, including fibroblast growth factor (FGF), which acts by stimulating tissue synthesis.…”

“…Therefore, due to muscle damage caused by exposure to GBH, there may be an imbalance in the proliferation of growth factors involved in muscle regeneration and mesenchymal growth, including fibroblast growth factor (FGF), which acts by stimulating tissue synthesis. connective tissue, especially in the synthesis of collagen I, which determines the tensile strength and rigidity of the tissue (45). In this sense, a structural alteration, such as an increase in fibrotic tissue, can negatively impact the arrival of muscle growth signalling factors.…”

Ultrastructural and Molecular Development of the Myotendinous Junction Triggered by Stretching Prior to Resistance Exercise

“…Three sessions of passive stretching demonstrated an anti-fibrotic process through a TGF-β1 mRNA reduction in elderly female Wistar rats (Martins et al, 2020). Despite the resistance training effects on the TGF-β1 protein level, our findings revealed the lower TGF-β1 protein in adult Wistar rats submitted to static stretching, isolated, and combined with resistance training.…”